NAIROBI, May 8 (Xinhua) -- Kenya's Health Ministry on Tuesday launched a polio vaccination campaign in the capital city of Nairobi, following a detection of a virus Eastleigh estate in eastern Nairobi late last month.

Jackson Kioko, the Director of Medical Services, told journalists in Nairobi that the vaccination will be conducted within Nairobi city estates.

"We are targeting to vaccinate 800,000 children in the next five days," Kioko said, adding that another vaccination exercise that targets 2.4 million children will be conducted during June-July period as part of plan to make Kenya polio free.

Kioko noted that the vaccinations will target 12 high risk counties that are mostly in Northern Eastern and Central Kenya.

Kioko further noted that the government is now resorting to weekly environmental sampling screening as opposed to doing it twice a month until further notice.

He said the country is currently developing a polio response plan that includes environmental surveillance and social mobilization in all parts of the country.

The official also said plans are underway to screen all children below age 15 at Kakuma and Dadaab refugee camps in northern Kenya

"We have intensified cross border surveillance along Kenya-Somalia border to help reduce infections from the neighboring country," he added.

Ruddy Eggers, the World Health Organization (WHO) Kenya Country Representative, challenged Kenya to move with speed to contain the virus from spreading to other regional countries.

He pledged 500,000 U.S. dollars to help Kenya contain the outbreak through routine immunization exercise especially along the Kenya-Somalia border.

According to the Ministry of Health, an estimated 1.7 million children born between 2013 and 2017 did not receive all the scheduled vaccines.